JPH04242913A - Electrolytic capacitor - Google Patents

Abstract

PURPOSE:To enable both short-circuiting failure rate and impedance characteristics of an electrolytic capacitor to be improved by obtaining an electrolytic paper with a low density, an intricate appearance and an improved pulling force resistance. CONSTITUTION:A desired electrolytic paper is produced by including 20wt.% or more pineapple pulp in a mixed material depending on a thickness and a density of the electrolytic paper to be produced. A pineapple fiber has an extremely small fiber diameter and is flexible and CSF numeric value of the pulp itself is 350cc and is extremely small as compared with Manila linen and sisal pulp so that it is not necessary to reduce the value of CSF by beating treatment when mixing with other natural fibers. Further, the Manila linen pulp or sisal pulp which is 80wt.% or less is blended as a raw material to be mixed. Also, the electrolytic paper is 30-60mum thick and 0.30-0.70g/cm<3> dense.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an electrolytic capacitor constructed by interposing electrolytic paper between an anode foil and a cathode foil, and in particular, it has a low density, a dense appearance like paper, and a tensile strength. This invention relates to improving both short-circuit failure rate and impedance characteristics by using a new electrolytic paper with good strength.

0002

[Prior Art] Generally, electrolytic capacitors, especially aluminum electrolytic capacitors, are made by winding electrolytic paper between an anode aluminum foil and a cathode aluminum foil to form a capacitor element. It is manufactured by immersing it in liquid to impregnate it with electrolyte and sealing it. The electrolyte usually uses ethylene glycol (EG), dimethylformamide (DMF), or γ-butyrolactone (GBL) as a solvent, and organic acid salts such as boric acid, ammonium adipate, and ammonium hydrogen maleate are dissolved in these solvents. It is manufactured by infiltrating the capacitor element from both ends using a material.

Since these conventional aluminum electrolytic capacitors have electrolytic paper impregnated with an electrolytic solution, the impedance characteristics as a capacitor, especially the equivalent series resistance (hereinafter referred to as ESR)
Therefore, in order to improve the impedance characteristics, in addition to lowering the resistance of the electrolytic solution, making the electrolytic paper thinner or lowering its density, it is necessary to use the raw material of the electrolytic paper from ordinary wood kraft pulp. Methods of changing to softwood wood pulp, Manila hemp pulp, esparto pulp, etc. are used. However, when the resistance of the electrolyte is lowered,
It causes corrosion to aluminum foil, and on the other hand, if the electrolytic paper is made thinner or has a lower density, the failure rate of short circuits increases when it is wound around a capacitor element, and even if there is no short circuit, it may not be commercialized. The problem is that the short-circuit failure rate is high after the product is put on the market.

[0004] Therefore, in order to reduce the short-circuit defect rate, the thickness of the electrolytic paper should be increased, the density should be increased, and if the density is the same, the JI, which indicates the degree of beating of the pulp that is the raw material, should be used.
CSF (Canadian) by SP 8121
If you reduce the value of Standard Freeness), the pulp fibers will fibrillate and become finer.
It is known that the obtained electrolytic paper becomes dense and the short defect rate is improved. In addition, the ESR of these items
It has been found that increasing the thickness of electrolytic paper deteriorates the ESR in a first-order manner, and increasing the density deteriorates the ESR in a second-order manner. That is, in order to improve the ESR, it is necessary to make the electrolytic paper thinner and lower its density, contrary to improving the short-circuit failure rate.

[0005] Therefore, improvement of short defect rate and ESR
In order to achieve both of the objectives of improving Attempts have been made to produce thin, low-density, and dense electrolytic paper. The mixed paper that is currently most commonly used as electrolytic paper is a mixed paper of Manila hemp pulp and esparto pulp. By mixing esparto pulp, which has a thin fiber diameter and high rigidity, with Manila hemp pulp, it has the rough appearance of Manila hemp. It is possible to obtain an electrolytic paper having compactness even if the density is low (Japanese Patent Publication No. 45372/1983).

Furthermore, by using sisal pulp as a raw material for electrolytic paper, the density of the paper produced does not easily increase even if the raw material is beaten to reduce the CSF value.
It has been proposed to obtain an electrolytic paper with a low density using a raw material with a small amount (Japanese Patent Application Laid-Open No. 126622/1983).

[0007]

[Problems to be Solved by the Invention] However, it has been found that the special patent published in Showa 61 was made by mixing the Manila hemp pulp and esparto pulp.
In No.-45372, since esparto pulp is very rigid, it is not compatible with Manila hemp pulp, and the tensile strength is extremely reduced by mixing esparto pulp. For this purpose, it is necessary to reduce the CSF value of Manila hemp pulp, generate countless fibrils, increase hydrogen bonds between fibers, increase the strength of electrolytic paper, and maintain tensile strength. However, recently, the fibrils of Manila hemp pulp used to increase tensile strength have filled the fiber gaps, so even though low-density paper can be made in the presence of rigid esparto pulp, it has a negative impact on ESR. It has become clear that there is.

On the other hand, according to JP-A-62-126622, which uses sisal pulp as a raw material, sisal pulp has approximately the same fiber diameter as Manila hemp pulp and is more rigid than Manila hemp pulp, so thin paper can be made. It has been found that the defect rate due to short circuits increases due to the problem that it is difficult to clean and has a rough appearance.

The present invention has been made in view of the above, and uses electrolytic paper that has low density, has a dense appearance as paper, and has good tensile strength, thereby reducing the short-circuit defect rate and impedance. The object of the present invention is to provide an electrolytic capacitor that improves both characteristics.

00010]

[Means for Solving the Problems] In order to achieve the above object, the present invention focuses on pineapple pulp as a raw material for electrolytic paper, and consists of an electrolytic paper interposed between an anode foil and a cathode foil. The main object of the present invention is to obtain an electrolytic capacitor characterized in that the electrolytic paper is made using at least 20% by weight of pineapple pulp as a raw material.

[00011] The electrolytic paper has a composition in which 20% by weight or more of pineapple pulp and 80% by weight or less of manila hemp pulp is blended, and a composition in which 20% by weight or more of pineapple pulp is blended and 80% by weight or less of sisal pulp is blended. The structure is as follows.

[00012] Further, the electrolytic paper has a thickness of 30 to 60 μm.
m, and the density is 0.30 to 0.70 g/cm3.

[00013] Furthermore, the electrolytic paper is characterized in that it is manufactured using a paper machine having one cylinder-type paper-making net or two or more cylinder-type paper-making nets.

00014

[Function] According to the present invention according to the above means, the fiber cross-sectional diameter of pineapple pulp is about 5 μm, which is compared to the fibers of esparto pulp, which is conventionally used in electrolytic paper and is said to have the smallest fiber diameter and good ESR. It is even smaller than approximately 10 μm, and does not have the rigidity of esparto pulp fibers, but has appropriate flexibility as electrolytic paper, so it is compatible with other natural fibers. Furthermore, it has the characteristic of having a good circular fiber shape in cross-section that does not impede the flow of electricity.

That is, the diameter of the fibers of pineapple pulp is about 1/4 that of Manila hemp pulp and about 1/2 that of esparto pulp, and since it is flexible, it can be processed without beating to generate fiber fibrils. When mixed with other natural fibers, it becomes entangled between the fibers, fills the voids appropriately, and can increase the tensile strength and denseness of the electrolytic paper. Since the bonds between these fibers are not hydrogen bonds in fine fibrils caused by beating, but superfine fibers overlap, it is possible to make electrolytic paper that does not impede the flow of electricity and has a homogeneous texture and density. This made it possible to obtain a new electrolytic paper that has low density, a dense appearance similar to paper, and good tensile strength, and an electrolytic capacitor made using electrolytic paper containing this pineapple pulp. can improve both ESR and short failure rate.

00016

[Embodiments] The structure of the present invention will be explained below based on the embodiments. First, as a raw material for electrolytic paper, carefully selected pineapple pulp raw hemp is cut into 1 to 2 mm pieces using a crusher, and N
Cook and pulp in aOH solution. The pulped pineapple fiber has a very small fiber diameter of approximately 5 μm and is flexible, and the CSF value of the pulp itself is 350.
Since the cc is much smaller than Manila hemp pulp's 720 cc and sisal pulp's 730 cc, there is no need to reduce the CSF value by beating when mixing with other natural fibers and making paper. Depending on the thickness and density of the electrolytic paper to be made, the mixed material may contain 20% by weight or more of pineapple pulp to make the desired electrolytic paper. The electrolytic paper thus obtained is interposed between an anode aluminum foil and a cathode aluminum foil and wound around it, impregnated with a liquid electrolyte, and sealed to produce an electrolytic capacitor. The present invention is characterized by the use of pineapple pulp as a raw material for electrolytic paper, and pineapple pulp as a raw material can be washed, washed, and treated like conventional Manila hemp pulp and esparto pulp.
After going through known raw material preparation processes such as dehydration and dust removal, a cylinder paper machine with one cylinder-type paper machine (circle-mesh single layer paper) or a cylinder machine with two or more cylinder-type paper machines is produced. Paper is made using a paper machine such as a mesh multilayer combination machine (circular mesh multilayer paper). In this circular mesh multilayer electrolytic paper, a synergistic effect is exhibited due to the denseness due to the use of pineapple fibers and the cancellation of pinholes in each paper due to the multilayer paper.

[00017] Other pulps to be blended with pineapple pulp are not particularly limited and may be Manila hemp pulp, sisal pulp, or softwood kraft pulp, but pineapple pulp must be used in an amount of at least 20% by weight of the raw materials when blending. There is. Therefore, other pulps are naturally 8
The mixing ratio is determined by the amount of pineapple pulp.

[00018] The thickness of the obtained electrolytic paper is 30~
Good results were obtained with a thickness of 60 μm and a density of 0.30 to 0.70 g/cm 3 .

[00019] In the present invention, the desired electrolytic paper can be obtained simply by mixing pineapple pulp, which is ultra-fine, flexible, and has a small CSF value of the pulp itself, with other raw materials. When making paper, there is no need to reduce the CSF value through beating treatment, and the beating process, which has the greatest impact on quality among electrolytic paper making technologies and is operationally complicated, can be omitted, and the quality of electrolytic paper can be stabilized. can be achieved. The mixing ratio will change as the density of the electrolytic paper decreases.
The mixing ratio of pineapple pulp with a small CSF may be reduced, and the mixing ratio may be increased as the density increases.

[00020] The electrolytic paper obtained in this way has a uniform structure and is denser than the electrolytic paper bonded with irregularly shaped microfibrils produced by conventional beating treatment, and the electrolytic paper after being impregnated with an electrolytic solution has Since the flow of electricity is good and the tensile strength is also good, an electrolytic capacitor made using electrolytic paper containing this pineapple pulp can improve both ESR and short-circuit failure rate.

[00021] Tables 1 to 3 below show electrolytic paper made using the pineapple pulp according to the present invention, which is made to approximately the same thickness and density, using a cylinder paper machine as a raw material, and conventional Manila hemp pulp, esparto pulp, Electrolytic capacitors were prepared using electrolytic paper made from sisal pulp and a mixture thereof, and the results of measuring the thickness, density, tensile strength, airtightness, short-circuit failure rate, and ESR are shown. Note that the method for manufacturing and measuring the electrolytic capacitor in the above example is as follows.

(1) Method for making an electrolytic capacitor Electrolytic paper is interposed between the tabbed anode foil and the cathode foil so that the two electrodes do not contact each other, and after winding up an electrolytic capacitor element, a predetermined electrolytic solution is added. The aluminum dry capacitor was impregnated with 50WV, 220μF and sealed in a case, and then aged.

(2) Evaluation method of electrolytic paper Thickness of electrolytic paper,
Density and tensile strength were measured by the method specified in JIS C2301 (electrolytic capacitor paper). The airtightness was measured using a B-type tester (Gurley densometer) in accordance with the section "12.1 Airtightness" stipulated in JIS C 2111 (Electrical Insulating Paper Testing Method). However, an adapter with a hole diameter of 6 mm was used.

(3) Evaluation method for electrolytic capacitors ■ Short-circuit failure rate After creating an electrolytic capacitor element by winding electrolytic paper together with anode foil and cathode foil, conduction due to a short between the two electrodes is determined without impregnating it with electrolyte. Confirmed with a tester. Approximately 1,000 devices were tested for the short-circuit defective rate, and the ratio of short-circuited devices to the total number of devices was defined as the short-circuit defective rate.

■ ESR (Equivalent Series Resistance) The ESR of an electrolytic capacitor is -40°C and LC at a frequency of 1000Hz.
Measured using an R meter.

[00026]

[Table 1]

[00027]

[Table 2]

[00028]

[Table 3]

As shown in the measurement results in Tables 1, 2, and 3, electrolytic paper containing pineapple pulp or using it alone has improved ESR and short-circuit failure rate compared to conventional electrolytic paper. Furthermore, it is clear that the tensile strength is significantly improved.

[00030] For example, Example 1 in Table 1 was made into a paper with a thickness of 50.0 μm and a density of 0.321 g/cm3 using raw materials of 20% by weight of pineapple pulp and 80% by weight of Manila hemp pulp, and Comparative Example 1 The paper was made using 100% manila to approximately the same thickness and density as in Example 1.

Although they have approximately the same thickness and density, by adding 20% by weight of pineapple pulp, the tensile strength of Example 1 is improved from 1.2 kg of Comparative Example 1 to 1.6 kg. Furthermore, the airtightness, which is an indicator of compactness, has increased from 0.5 seconds to 1.0 seconds. As a result, the short-circuit failure rate of electrolytic paper ranged from 12.3% to 9.
．． 7%, and the ESR has both been improved from 1.048Ω to 0.964Ω.

Similarly, in Example 3 of Table 2, the raw materials were 60% by weight of pineapple pulp and 40% by weight of Manila hemp pulp, and the thickness was 40.2 μm and the density was 0.510 g/cm3.
The short-circuit defect rate of the electrolytic paper produced in
is 1.513Ω, tensile strength is 4.5kg, airtightness is 14
, 2 seconds. On the other hand, Comparative Example 3 is an electrolytic paper made with approximately the same thickness and the same airtightness using a mixed raw material of 60% by weight of Esparto pulp and 40% by weight of Manila hemp pulp, which are currently most commonly used. The rate is 3.2
%, ESR was 1.673Ω, tensile strength was 3.7kg, and airtightness was 9.5 seconds. As is clear from the data,
According to Example 3, the tensile strength was significantly improved by simply blending pineapple fiber without performing beating treatment, the formation of the electrolytic paper became uniform, the density was improved, and the short defect rate and ESR were improved. Both have been improved. In addition, in Example 4 in the same table, the paper was made using two circular mesh papermaking nets and 60% by weight of pineapple pulp and 40% by weight of sisal pulp, but the short defect rate was 1.7%, and the ESR was
At 1.369Ω, both the short-circuit failure rate and ESR were significantly improved compared to Comparative Examples 2 and 3. From this,
The two-layer electrolytic paper made of pineapple pulp, which is an ultra-fine fiber, has a synergistic effect due to the denseness of the pineapple fiber and the canceling out of the pinholes in each paper due to the double-layered paper. The effect is being obtained.

Further, Example 5 shown in Table 3 is an electrolytic paper using 100% by weight of unbeaten pineapple pulp, while Comparative Example 4 shows an electrolytic paper using 100% by weight Manila hemp and Comparative Example 5 shows an electrolytic paper using 100% by weight of Manila hemp. Compared to electrolytic paper using 40% by weight of Esparto pulp and 60% by weight of Manila hemp pulp, the tensile strength is significantly improved and the density of the electrolytic paper is also significantly increased, which not only improves the short defect rate. , the ESR is significantly improved.

[00034] As shown in Tables 1, 2, and 3, the CSF value of each example was smaller than the CSF value of the mixture with Manila hemp pulp or esparto pulp in the comparative example in Tables 1, 2, and 3. However, this value is unique to pineapple fibers, which are extremely small and flexible, and as in the comparative example, countless fibrils are generated by beating for the purpose of adjusting thickness and density or improving tensile strength.
It is clear that unlike the numerical value where F is made small, it does not inhibit the flow of electricity as electrolytic paper.

Therefore, according to the present invention, by blending unbeaten pineapple pulp into the raw material, the tensile strength can be significantly improved even at low density, and electrolytic paper having homogeneous texture and density can be produced. It became possible to make paper,
It is possible to improve both the short-circuit failure rate and ESR characteristics.

[00036]

[Effects of the Invention] As explained in detail above, the electrolytic capacitor according to the present invention focuses on pineapple pulp as a raw material for electrolytic paper, and has electrolytic paper interposed between an anode foil and a cathode foil. The electrolytic capacitor is characterized in that the electrolytic paper is made using at least 20% by weight of pineapple pulp as a raw material,
The following effects can be obtained.

That is, the diameter of the fibers of pineapple pulp is about 1/4 that of Manila hemp pulp and about 1/2 that of esparto pulp, and since it is flexible, it can be processed without beating to generate fiber fibrils. When mixed with other natural fibers, it becomes entangled between the fibers, fills the voids appropriately, and can increase the tensile strength and denseness of the electrolytic paper. Since the bonds between these fibers are not hydrogen bonds in fine fibrils caused by beating, but superfine fibers overlap, it is possible to make electrolytic paper that does not impede the flow of electricity and has a homogeneous texture and density. This made it possible to obtain a new electrolytic paper that has low density, a dense appearance similar to paper, and good tensile strength, and an electrolytic capacitor made using electrolytic paper containing this pineapple pulp. can improve both ESR and short failure rate. In addition, in the present invention, the desired electrolytic paper can be obtained simply by mixing pineapple pulp, which is extremely fine and flexible and has a small CSF value of the pulp itself, with other raw materials, so it can be mixed with other natural fibers. When making paper,
There is no need to reduce the CSF value through beating treatment, and the beating process, which has the greatest impact on quality among electrolytic paper manufacturing technologies and is operationally complex, can be omitted, and the quality of electrolytic paper can be stabilized. .

Claims (5)

[Claims] 1. An electrolytic capacitor comprising an electrolytic paper interposed between an anode foil and a cathode foil, wherein the electrolytic paper is made using at least 20% by weight of pineapple pulp as a raw material. electrolytic capacitor. 2. The electrolytic capacitor according to claim 1, wherein the electrolytic paper contains 20% by weight or more of pineapple pulp and 80% by weight or less of Manila hemp pulp. 3. The electrolytic capacitor according to claim 1, wherein the electrolytic paper contains 20% by weight or more of pineapple pulp and 80% by weight or less of sisal pulp. 4. The electrolytic paper has a thickness of 30 to 60 μm,
Claim 1, wherein the density is 0.30 to 0.70 g/cm3,
2. The electrolytic capacitor described in 2 and 3. 5. The electrolytic paper according to claim 1, 2, 3, or 4, wherein the electrolytic paper is made by a paper machine having one cylinder-type paper making net or two or more cylinder-type paper making nets. Electrolytic capacitor.